Driver with control interface facilitating use of the driver with varied DC-to-DC converter circuits

ABSTRACT

A driver for a DC-to-DC converter that may utilize a flyback or buck-boost converter circuit. The driver includes a driver circuit and an interface circuit. The interface circuit has a sensor sensing an input voltage from a DC supply and generating a sensor signal to a driver selector. The driver selector compares the sensor signal to a comparison voltage to determine the type of converter circuit and then transmits a selector signal to a driver circuit where it is used to control one or more of the components of the driver circuit, such as the logic circuit which is used for driving the converter to regulate the converter output. The sensor includes a sense resistor along with a current-sense amplifier, which is adapted for connection to a high side or a low side of a power supply while still producing a substantially equivalent output voltage or sensor signal.

BACKGROUND OF THE INVENTION

1. Related Applications

This application claims the priority benefit of Chinese applicationSerial No. 200410035040.6 filed on Apr. 16, 2004, the full disclosure ofwhich is incorporated herein by reference.

2. Field of the Invention

The present invention relates generally to voltage converters, and moreparticularly, to a driver with a smart or adaptive interface that allowsthe driver to be used in varied direct current (DC) to direct-current(DC) converters utilizing differing types or configurations of convertercircuits, such as buck-boost and flyback DC-to-DC converter circuits,without modification of the driver.

3. Relevant Background

Direct-current (DC) to direct-current (DC) converters are well known inthe field of electronics. DC-to-DC converters are typically employed toconvert from one DC voltage level to another DC voltage level. They areused in a variety of environments. For example, DC-to-DC converters areused to provide a supply voltage to microprocessors and other logicdevices and are also used in many electronic systems to provide supplyvoltage, such as in a disk drive where the converter supplies a desiredvoltage to a voice coil motor and spindle motors. The voltage source maybe a battery, such as in a notebook or handheld computer or electronicdevice, or some other power source that provides a DC voltage, such as 1to 36 V. The DC-to-DC converter functions to convert this supply orinput voltage to one or more regulated output DC voltages required bythe load, i.e., the microprocessor, the motor driver, and the like. Forexample, many logic devices on integrated circuits (ICs) work on 1.2,3.6, and 5 V supplies from a converter while the power source supplies12 V or other supply voltage. The DC-to-DC converter may be provided aspart of an integrated circuit (IC) such as on an IC with amicroprocessor or on a separate IC or provided as part of a standardcircuit in other applications.

There a variety of DC-to-DC converters designs, such as pulse-widthmodulated (PWM) converters and pulse-frequency modulated (PFM)converters, but generally each of the DC-to-DC converters includes aconverter circuit and a driver. The converter circuit converts the inputor supply voltage into a desired output or load voltage. The driverfunctions to provide control signals to the converter circuit toregulate the output or load voltage produced by the converter circuit.There are presently numerous converter circuits utilized in DC-to-DCconverters. Two common converter circuits are labeled flyback convertersand buck-boost converters based on their functioning and the arrangementof their circuit components. Other converters circuits include boostconverters and buck converters.

To drive these converters, a driver is designed that include a varietyof circuitry and components. For example, a common implementation of adriver includes blocks or devices to generate a reference voltage foruse in regulating the output of the converter circuit, a feedback tosample the converter circuit output, a circuit for generating an errorsignal based on the reference voltage and the feedback signal, amodulator for modulating the output based on the error signal (such as apulse-width modulator in a PWM converter), additional control components(e.g., a component for limiting the maximum duty cycle of the modulatorsignal, a current limitation device for limiting the current of atransistor in the converter circuit, and a voltage lock out circuit forswitching on and off circuits in the driver based on the level of theinput power), and a logic circuit for combining the signals of the othercomponents and providing a drive signal to the converter circuit toregulate the converter circuits output.

To design or create a DC-to-DC converter, a driver is paired with one ofthe converter circuit types. In some cases, the driver is manufacturedseparately from the converter circuit, e.g., in two separate ICs.However, a driver is typically configured to drive a single type ofconverter circuit and cannot be used in multiple converter applications.For example, a driver may be designed and manufactured for use orpairing with a buck-boost converter circuit that includes a P-channelswitching transistor. In other words, the driver is configured toprovide a drive or output signal to drive this particular type oftransistor. Without modification, this specially configured drivercannot be used with a flyback converter circuit, which includes anN-channel switching transistor. Presently, this problem is addressed bydesigning and manufacturing a unique driver for each of the convertercircuits and by combining these differing drivers with the differingconverter circuits to manufacture DC-to-DC converters. Redesigning thedrivers for different types of converter circuits results in undesirableand often, unacceptable increased engineering and manufacturing costsassociated with the produced DC-to-DC converters.

Hence, there remains a need for a driver for DC-to-DC converters that iscompatible with more than one converter circuit type and is thusinterchangeable. Preferably, such a driver would be able to interfacewith different converter circuits with minimal or no modification, wouldbe relatively easy to produce with low associated costs with knownexisting manufacturing capabilities, and would be readily accepted bythe electronics industry as providing effective control and/orregulation of the output of the converter circuit.

SUMMARY OF THE INVENTION

The present invention addresses the above problems by providing a driverfor driving a converter circuit for a DC-to-DC converter. The driverdesign is unique in part because the convert circuit may be one of anumber of converter types such as a flyback converter and a buck-boostconverter and the driver is able to produce a driver signal to drive theconverter without modification to the driver. In this regard, the driverincludes a driver circuit having a number of components that act incombination to generate a regulated voltage from an input voltage from apower source, such as a battery or other DC source. For example, thedriver circuit may be a PWM driver with blocks or elements such as alogic circuit for generating the driver signal provided to the convertercircuit based on operation and input from a pulse width modulator, acurrent limitation element, a maximum DT limitation element, a V_(REF)element, a feedback block linked to the converter circuit, and an undervoltage lock out circuit. The operation of one or more of these blocksis controlled by an interface circuit which operates to sense thevoltage input from the supply and to provide a drive selector signal toone or more of the blocks of the driver circuit to cause the blocks tooperate properly for the detected type of converter. In one embodiment,the driver selector signal is provided to the logic circuit, the currentlimitation block, and the maximum DT limitation element but in otherembodiments more or less blocks are controlled by the interface circuit.In this manner, the driver circuit is able to automatically adapt itsoperation to the type of converter circuit without requiringmodification or manufacturing of multiple drivers for differingconverter circuit types or modes.

More particularly, the interface circuit includes a voltage sensor thatfunctions to sample the input voltage and in response, to a sensorsignal. The interface circuit also includes a driver selector forcomparing the sensor signal with a preselected voltage level orcomparison voltage and based on the comparing generating the driveselector signal that is provided to the driver. In some embodiments, acomparator is provided in the selector to perform the comparingfunction. The voltage sensor generally includes a sense resistor forusing in sensing the input voltage and more typically, includes acurrent-sense amplifier for generating the sensor signal. In oneembodiment, the current-sense amplifier is adapted to be a high/lowcurrent-sense amplifier that can be connected to either the high or lowside of the DC power source and still provide a substantially equivalentoutput voltage or sensor signal. Briefly, this is achieved with aswitching device that operates based on the comparison of a sensedvoltage to a preset reference voltage to select the use of a firstcircuit when connected to the high side or a second circuit whenconnected to the low side. The first and second circuits include matchedinput resistor devices with substantially equivalent resistance andadditionally the first or high-side circuit (at least in one embodiment)includes an operational amplifier and a pair of current mirrorsconnected in cascade and the second or low-side circuit includes anoperational amplifier and a current mirror (each of the current mirrorstypically having a different configuration).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram of system in which a DC-to-DCconverter according to the present invention is used to convert voltagefrom a power source to a voltage output to a load;

FIG. 2 is a block circuit diagram of DC-to-DC converter, such as theconverter shown in FIG. 1, configured according to the invention with adriver interface control circuit operating a driver for use with aconverter circuit which may have differing configurations;

FIG. 3 is a block circuit diagram of a DC-to-DC converter according tothe invention in which the drive interface control circuit and driver ofFIG. 2 are used, without modification, with a buck-boost convertercircuit;

FIG. 4 is a block circuit diagram of a DC-to-DC converter similar toFIG. 3 in which the drive interface control circuit and driver of FIG. 2are used, without modification, with a flyback converter circuit;

FIG. 5 is a circuit diagram of a known current sense amplifier that maybe utilized as the voltage sensor of the driver interface controlcircuit of the invention, such as in the control circuit shown in FIGS.1-4;

FIG. 6 is a circuit diagram similar to FIG. 6 of another known currentsense amplifier that may be utilized as the voltage sensor of the driverinterface control circuit of the present invention, such as in thecontrol circuit of FIGS. 1-4;

FIG. 7 is a high/low side current sense amplify circuit that may be usedfor the voltage sensor of the driver interface control circuit (or inother applications) of the present invention in place of the amplifiersshown in FIGS. 5 and 6; and

FIGS. 8-10 illustrate useful embodiments of the current mirrors of thecurrent sense amplify circuit shown in FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to providing a design solution thatenables a single driver design or configuration to be utilized with twoor more converter circuits in a DC-to-DC converter. In DC-to-DCconverters configured according to the invention, a compatibleinterface, i.e., a driver interface control circuit, is provided for andlinked to a driver to detect or sense the type of converter circuitemployed in the DC-to-DC converter and to control operation of thedriver based on the detected or sensed type of converter circuit. Inthis manner, the driver and interface circuit combination of theinvention can be used widely to enhance system design and manufacturingefficiency. The sensing of the converter circuit is an important featureof the invention, and one aspect of the invention is directed toproviding a voltage sensor that includes a current sense amplifiercircuit that can be used on either the high side or low side of a powersupply, which significantly increases the current sensors flexibilityespecially in integrated circuit (IC) applications. Briefly and as willbecome clear from the following description with reference to FIGS.7-10, the new current sense amplifier circuit uses an automaticcontroller switch to achieve a good power supply rejection ratio, toprovide accurate current gain control, to use a low V_(CC), and to beuseful with a wide range of voltages.

FIG. 1 illustrates a system 100 that incorporates the driver interfaceconcepts of the present invention. System 100 may be implemented in partor in its entirety on one or more ICs, e.g., the DC-to-DC converter 110may be an IC, the driver interface control circuit and driver 112 may bean IC, the load 104 may be a logic device on the same or different IC asthe DC-to-DC converter 110 or as one or more of the components of theconverter 110. As shown, the system 100 is a typical system in which aDC voltage is converted by a converter to another DC voltage used by aload to operate. The system 100 includes a DC power source 102, such asa battery and the like, that provides DC power at one or more voltages,such as 1-36 VDC. A DC-to-DC converter voltage converter 110 is linkedto the DC power supply 102 to receive the supply or input voltage,V_(IN) or V_(POS), and to convert the voltage to a load or output DCvoltage, V_(OUT), that is passed to a load 104 (e.g., another circuit orsystem or a device such as a logic device, microprocessor, motorcontroller, and the like).

The DC-to-DC converter 110 is configured according to the presentinvention with an adaptable driver such that a variety of convertertypes may be utilized within the DC-to-DC converter 110. As shown, aconverter 114 is provided for converting the voltage in, V_(IN), toanother voltage, V_(OUT), and in this regard, may be any of a number ofconverter types, such as but not limited to a buck converter, a boostconverter, a buck-boost converter, or a flyback converter. The converter114 is driven or regulated by a driver 118, which in turn is controlledby a driver interface control circuit 112. The driver 118 may take anumber of configurations that are known in the electronic arts (such asthe PWM driver 218 shown in FIG. 2) and the particular configuration ofthe driver is not limiting to the invention as different driverconfigurations may be used within the DC-to-DC converter 110.

The driver interface control circuit 112 is shown to be positioned inthe DC-to-DC converter 110 between the DC power source 102 and thedriver 118 and converter 114 to sample or sense the input voltage,V_(IN), and in response, to transmit a control signal or a selectoroutput signal to the driver 118, thereby controlling operation of thedriver 118 based on a determined type of converter 114. In other words,the selector output from the control circuit 112 will vary with both thesensed voltage input, V_(IN), and on the type of converter 114 detectedor sensed. To provide these functions, the driver interface controlcircuit 112 includes a voltage sensor 120 that acts to sense thevoltage, V_(IN), at a sample point and to transmit a sensor signal,e.g., the sensed voltage, to a driver selector 130. In one embodiment,the driver selector 130 functions to compares the sensor signal to apredetermined voltage level, e.g., a comparison voltage, V_(COMP), andin response to such comparison, to transmit a selector output signalthat is used to control operation of the driver 118, i.e., by effectingoperation of one or more of the components within the driver 118.

While the invention may be used with a variety of driver configurations,it may be useful to illustrate the interface concepts implemented with arelatively standard driver implementation, i.e., a pulse-width modulator(PWM) driver. Referring to FIG. 2, a DC-to-DC converter 210 is shownthat is configured according to the invention with a converter circuit214 for converting an input DC voltage, V_(POS), to another voltageuseful by a load (not shown). In between the converter circuit 214 andthe voltage source, a driver 218 is provided for driving the convertercircuit 214 with a driver output signal. The driver output signal isregulated or selected in part based on a converter selector outputsignal from a driver interface control circuit 212 linked to the inputvoltage line and to the driver 218 (and, typically, to the convertercircuit 214 as shown in FIGS. 3 and 4).

The driver 218 includes a number of components that work in combinationto produce the driver output signal and one or more of these componentsare controlled by a selector signal from the driver interface controlcircuit 212. The exemplary driver 218 is illustrated to have arelatively standard set of components and arrangement of thesecomponents, but other embodiments of the invention may includeadditional components, include fewer components, and/or include adifferent circuit or arrangement of such components. As shown, thedriver 218 includes a current limitation element or block 240 that isused to limit the maximum current of a switching transistor (see, forexample, the converter circuits shown in FIGS. 3 and 4) by providing asignal to a logic circuit 260. The logic circuit 260 generates thedriver output signal and, briefly, functions to combine the signals fromthe other components of the driver 218 and although not shown, is usedto drive with the driver output signal the external switching transistorof the converter circuit 214. A maximum DT limitation block 242 isprovided in the driver 218 for limiting the maximum duty cycle of thePWM signal from the pulse-width modulator 256. The V_(REF) element 246is provided for generating a reference voltage, and the regulated outputvoltage of the converter circuit 214 is proportional to this voltage.

The V_(REF) element 246 provides a signal to the error signal block orelement 248 which functions to generate an error signal or error amp tothe PWM 256 by comparing the reference voltage with the feedback signalreceived from the feedback block 250. The feedback block 250 is used tosample the regulated output voltage of the converter circuit 214 andprovide a feedback signal to the error signal block 248. The UVLO (undervoltage lock out) circuit 254 is included to switch on and offcorresponding circuits or elements of the driver 218 according to alevel of the power supply or input voltage, V_(POS). The PWM 256provides a signal to the logic circuit 260 and the pulse-widthmodulation is the width of pulse signal generated by the error signalfrom the error amp or signal block 248.

To enable the driver 218 to interface with the converter circuit 214without modification to suit the configuration or type of the circuit214, the driver interface control circuit 212 is provided to sample theinput voltage, V_(POS), and to determine the type or configuration ofthe converter circuit 214, and in response, to transmit a selectoroutput or control signal to one or more of the driver 218 components tocontrol their operations. To generate the selector output or drivercontrol signal, the driver interface control circuit 212 includes asensor 220 and a driver selector 230. The sensor 220 includes a senseresistor 222 and functions to sense the voltage, V_(POS), at a samplepoint that may be before the converter circuit 214 as shown or after theconverter circuit 214 (such as that shown in FIG. 4). The sensor 220then sends a sensor signal to the driver selector 230 for “selecting” aconverter type. This selecting is achieved in the illustrated embodimentby a comparator 232 that compares the sensor signal with the voltage,V_(COMP). The comparator's output is the selector output that is used tocontrol one or more elements or blocks of driver 218. For example, asshown, the selector output is passed to the current limitation 240, themaximum DT limitation 242, the error signal, feedback, and logic circuit260 blocks or elements. In this fashion, the driver 218 is controlled bythe driver interface control circuit 212 in order to properly interfacewith the converter circuit 214 without the need for modifying the driver218 to suit the configuration of the converter circuit 214 (i.e.,interface without regard to the type of converter used in the DC-to-DCconverter 210).

With an understanding of the broader principles of the inventionunderstood, a description of a couple of specific DC-to-DCimplementations with drivers and driver interface control circuits ofthe invention are provided with reference to FIGS. 3 and 4.Specifically, the proposed driver with interface circuitry are shown inuse (without modification) in both a buck-boost DC-to-DC converter and aflyback DC-to-DC converter. These are two of the main types or modes ofconverter circuits presently in use, and are, therefore, useful forillustrating how the driver/interface combination of the presentinvention will have wide spread and effective use in the electronicsindustry.

A DC-to-DC converter 300 is shown in FIG. 3 with a buck-boost converter314. The DC-to-DC converter 300 includes the driver interface controlcircuit 212 as shown and explained with reference to FIG. 2 along withthe driver 218 as also shown in FIG. 2. The driver interface controlcircuit 212 is connected so as to sample the input voltage, V_(POS),from a voltage source (such as source 102 of FIG. 1). The sensor 220 isfurther linked to the converter 314 (and, specifically, to the sourceside of switch 360, e.g., a MOSFET and the like, via line 374) to passthrough the supplied voltage, VPOS, to the converter 314 for conversionto an output voltage (e.g., across load resistor 324). The selectoroutput is passed to the driver 218 from selector 230 via connection atnode 310. Note, the selector 230 of control circuit 212 is shown in FIG.2 to drive different components of the driver 218 that is shown in FIG.2, and particularly is shown to control operation of the currentlimitation block 240, the maximum DT limitation block 242, and, at leastin part, the logic circuit 260. The driver 218 is likewise linked to theconverter 314 for providing a driver output or control signal to theconverter (and, specifically, to the gate of the switch 360 via line372).

The converter 314 is a buck-boost converter that includes a switch 360(i.e., a P-channel switching transistor or the like) linked at thesource connection via the source line 374 to the voltage sensor 220 ofthe driver interface control circuit 212 and to the logic circuit 260 ofthe driver 218 at the gate connection via line 372 to receive the driveroutput signal. The drain connection of the switch 360 is connected inseries with a flywheel diode 340 and in parallel to the feedback block250 of the driver 218, a filter capacitor 330, an energy-storageinductor 350, and a load as shown by load resistor 324.

FIG. 4 illustrates a flyback mode DC-to-DC converter 400 being driven bysimilarly configured driver 218 without modification due to theinclusion of the driver interface control circuit 212. As shown, thedriver 218 is linked in parallel via the feedback block 250 to theconverter circuit 414 and via line 472 that is connected to the gate ofswitch 460 and the logic circuit 260 of the driver 218. The driverinterface control circuit 212 provides a control signal to the driver218 (i.e., to the current limitation block 240, the maximum DTlimitation block 242, and logic circuit 260) based on a voltage sampledon line 474 that is connected to the source connection of switch 460 andto the sense resistor 222 of the sensor 220. The sensor 220 provides asensor signal to the selector 230 where it is compared by comparator 232to a selected voltage, V_(COMP), and the selector 230 provides a controlor selector output signal to the driver components shown.

The converter circuit 414 is a flyback mode or type DC-to-DC converterand as such includes an energy-storage transformer 450 connected to theinput voltage, V_(POS), and to the drain of the switch 460, i.e., anN-channel MOSFET or switching transistor or the like. The convertercircuit 414 further includes a flywheel diode 440 in series with thetransformer 450 and a filter capacitor 430 in parallel with thetransformer 450. The converter 414 is connected to a load represented byload resistor 424 to provide a regulated output (or converted) voltagebased on the input voltage, V_(POS), and driver signal on line 472 fromthe logic circuit 260 of the driver 218.

In the DC-to-DC converters 300 and 400, the sensor 220 senses thevoltage of the P-channel switching transistor's source 374 or N-channelswitching transistor's source 474. The output of the sensor 220 is fedto the selector 230 where a comparator 232 compares the sensor signalwith the comparison voltage, V_(COMP). If the sensor signal is higherthan V_(COMP), the converter 314 or 414 is determined by the driverinterface control circuit 212 to be a buck-boost converter and if lower,than a flyback converter. The output of the control circuit 212 is thenused to control the corresponding blocks or components (i.e., as shown,in FIGS. 3 and 4, the current limitation block, the maximum DTlimitation block, and the logic circuit) of the driver 218 to allow thedriver to interface and drive the different types of converter circuits314, 414. The driver 218 is able to drive the differing convertercircuits 314, 414 without modification and automatically.

The voltage sensor 120, 220 of the driver interface control circuits112, 212 may take a number of forms to practice the invention. As shownin FIGS. 1-4, the sensor generally senses the sensor signal to thedriver selector 130, 230 used for comparison with a voltage, V_(COMP),that can be set for comparator 230. In some embodiments, the sensor 120,220 includes a current-sense amplifier to facilitate generating thesensor signal. FIGS. 5 and 6 illustrate two classical current-senseamplifiers 500 and 600 that may be used as part of the voltage sensor120, 220 to provide a sensor signal to the driver selector 130, 230. Asthese amplifiers 500, 600 are relatively standard devices, theircomponents and operation is not explained in detail because it will beunderstood by those skilled in the art from the circuit drawings ofFIGS. 5 and 6.

Briefly, though, the current-sense amplifier 500 of FIG. 5 is for use inhigh-side sensing on a positive supply (such as with source 102 of FIG.1). The amplifier 500 is configured to use an NPN transistor in thecomparator A1's input stage. In operation, the current-sense amplifier500 is connected in DC-to-DC converters 100, 210, 300, 400 such that thelarge load current, I_(LOAD), flows through the sense resistor,R_(SENSE) (e.g., resistor 222 of FIGS. 2-4) from the R_(S)+ node to theconnection with the converter 114, 214, 314, 414. Current also flowsthrough R1, Q3, and Q1 and an output voltage signal (i.e., sensorsignal) is generated by flow through output resistor, R3.

In contrast, the current sense amplifier 600 of FIG. 6 is for use inlow-side sensing on a negative supply (such as with source 102 of FIG.1). The amplifier 600 is configured to use the PNP transistor in A2'sinput stage. In operation, the current-sense amplifier 600 is connectedin DC-to-DC converters 100, 210, 300, 400 such that the current,I_(LOAD), flows through the sense resistor, R_(SENSE) (e.g., resistor222 of FIGS. 2-4) to the connection with the converter 114, 214, 314,414. A voltage signal or sensor signal is generated by current flowdirected through the output resistor, R3. As noted, the amplifiers 500,600 are only useful, respectively, for use on the high side or low sideof the power supply. The amplifiers 500, 600 (and amplifier 700 of FIG.7) are often incorporated in an IC, and it is desirable to provide acurrent-sense amplifier that is more flexible in its use andapplications.

In this regard, the invention includes the current-sense amplifier 700of FIG. 7 that is able to sense a large current that can be either onthe high side or low side of the power supply. The current-senseamplifier 700 is further configured with an automatic controller switchto provide good PSSR, accurate gain control, and low V_(CC). The currentsense amplifier 700 is connected between the power supply (such assource 102) and converter circuits 114, 214, 314, 414 such that loadcurrent, I_(LOAD), flows in either direction through sense resistor 702(e.g., resistor 222 of FIGS. 2-4). The current-sense amplifier circuitryis connected on both sides of the sense resistor 702 at nodes 704 and706 and current flows through resistors R_(G1) and R_(G2) to providesensed current, CS− and CS+ to the other components of the amplifier 700at points 714, 716.

The high/low sense amplifier 700 can be thought of as constructed mainlyof operational amplifiers 720 and 760 (labeled OP1 and OP2) and currentmirrors 730, 736, and 750 (labeled CM1, CM2, and CM3) with connectinglines 716, 732, 738, 742, 744, 764, and 768. In a one embodiment, OP1720 has an input stage that uses a PNP transistor while OP2 760 has aninput stage that uses an NPN transistor (although other OP amps may beutilized to practice the invention). The amplifier 700 further includesa comparator 766 (labeled CMP) that is connected to line 764 and isincluded to provide a control signal, V_(C), to controlled switches 722,726 (labeled K1 and K2) to control the switches 722, 726 on or off bycomparing V_(CS+) and V_(REF) (e.g., 1.6 V and the like depending on thepower supply).

The current mirrors CM1, CM2 and CM3 730, 736, and 750 are precisioncurrent mirrors. While other configurations can be employed in theamplifier 700, FIGS. 8-10 illustrate exemplary circuits that can be usedfor the mirrors with the particular embodiments labeled CM1 830, CM2936, and CM3 1050. As shown, for CM1 830 and CM3 1050, transistors Q1and Q2 provide an accurate current mirror. Q3 and Q4 are matchedtransistors connected in cascade with transistors Q1 and Q2 for boostingthe output impedance. For CM2 936, transistors Q1, Q2, Q3, and Q4construct a Wilson current mirror.

Referring again to FIG. 7 with further reference to FIGS. 8-10, whenR_(SENSE) 702 is put on the high side of the power supply (e.g., V_(CS+)is higher than V_(REF)), V_(C) will be high thus making gate K1 722switch off and gate K2 762 switch on (as shown in FIG. 7). In this case,OP amp O1 720 and current mirror CM1 730 do not operate but OP amp O2760 and current mirrors CM2 and CM3 736, 750 do work or operate.Neglecting the input bias current of OP amp O2 760,I _(OUT)=(n)(I _(LOAD))(R _(SENSE) /R _(G2))

The output voltage of the current-sense amplifier 700 (or the sensorsignal) is provided by the current out, I_(OUT), flowing through theoutput resistor, R_(OUT) 770.

When R_(SENSE) 702 is put on the low side of the power supply (e.g.,V_(CS+) is lower than V_(REF)), V_(C) will be low which makes gate K1722 switch on and gate K2 762 switch off. In this state of the amplifier700, OP amp OP1 720 and current mirror CM1 730 are operational while OPamp OP2 760 and current mirrors CM2 and CM3 736 and 750 are notoperational or working. Neglecting the input bias current of OP amp OP1720,I _(OUT)=(n)(I _(LOAD))(R _(SENSE) /R _(G1))

Again, the output voltage of the current-sense amplifier 700 (or thesensor signal) is provided by the current out, I_(OUT), flowing throughthe output resistor, R_(OUT), 770. If R_(G1) 710 and R_(G2) 712 arematched resistors whose resistance values are substantially equal,whenever R_(SENSE) 702 is placed on the high or low side of a powersupply, the following equation is achieved (e.g., R_(G)=R_(G1)=R_(G2)):I _(OUT)=(n)(I _(LOAD))(R _(SENSE) /R _(G))

In this manner, the output voltage or sensor signal is substantially thesame whether the current-sense amplifier 700 of voltage sensor 120, 220is connected on the high or low side of the power source (such as source102 of FIG. 1).

The transistors of the current mirrors 730, 736, 750 (as shown inexamples of mirrors 830, 936, and 1050 of FIGS. 8-10) can provide a wideoutput voltage or sensor signal range. Gain can be calculated with thefollowing formula:V _(OUT) /V _(RSENSE)=(n)(R _(OUT) /R _(G))

From the equation, the gain can be set by adjusting the ratio of theresistor ROUT 770 and R_(G) (i.e., R_(G1) 710 and R_(G2) 712).

The above disclosure sets forth a number of embodiments of the presentinvention. Other arrangements or embodiments, not precisely set forth,could be practiced under the teachings of the present invention and asset forth in the following claims.

1. A driver for driving a DC-to-DC converter circuit that may have atleast two configurations for converting an input voltage from a powersource to a regulated voltage, comprising: a driver circuit having anumber of components acting to generate a driver output signal fordriving the DC-to-DC converter circuit to generate the regulatedvoltage; and a driver interface control circuit electrically connectedto the driver circuit transmitting a selector output signal to one ormore of the components of the driver circuit, the driver interfacecontrol circuit including a voltage sensor sensing the input voltage andgenerating a sensor signal corresponding to the sensed input voltage andincluding a driver selector receiving the sensor signal and generatingthe selector output signal to control operation of the driver circuit.2. The driver of claim 1, wherein the two configurations include abuck-boost converter and a flyback converter and wherein the selectoroutput signal is generated by the driver selector to indicate whetherthe DC-to-DC converter circuit comprises a buck-boost converter or aflyback converter.
 3. The driver of claim 2, wherein the voltage sensorincludes a sense resistor, the sense resistor electrically connected toa source of a transistor in the DC-to-DC converter circuit.
 4. Thedriver of claim 1, wherein the driver selector comprises a comparatorgenerating the selector output signal by comparing the sensor signal toa comparison voltage.
 5. The driver of claim 1, wherein the drivercomponents include a logic circuit for generating the driver outputsignal based on input from other ones of the driver components, thelogic circuit being connected to the driver selector and receiving theselector output signal.
 6. The driver of claim 5, wherein the othercomponents include a current limitation device and a maximum duty cyclelimitation device both linked to the driver interface control circuitand receiving the selector output signal, the operation of the devicesbeing based on the selector output signal.
 7. The driver of claim 1,wherein the voltage sensor comprises a current-sense amplifiergenerating the sensor signal.
 8. The driver of claim 7, wherein thecurrent-sense amplifier is operable in a first state and a second statecorresponding to connection of the current-sense amplifier to a highside and a low side, respectively, of the power source and wherein thesensor signal is substantially equivalent in the first and secondstates.
 9. The driver of claim 8, wherein the current-sense amplifierincludes means for selecting a first circuit or a second circuit forgenerating an output current that generates the sensor signal, theselecting comprising comparing a voltage input to the current-senseamplifier to a reference voltage.
 10. The driver of claim 9, wherein thefirst circuit includes a first operational amplifier and a first and asecond current mirror connected in series and wherein the second circuitincludes a second operational amplifier and a third current mirror. 11.The driver of claim 10, wherein the current-sense amplifier includes afirst and second resistor device for connecting to the high and the lowsides of the power source and to the first and second circuits,respectfully and wherein the first and second resistor devices havesubstantially equal resistance values.
 12. A DC-to-DC converter,comprising: a converter circuit for converting an input DC voltage to anoutput DC voltage, the converter circuit being configured as abuck-boost converter or flyback converter; a driver electricallyconnected to the converter circuit for providing a driver signal to theconverter circuit for driving the converter circuit; and an interfacecircuit electrically connected to the converter circuit and the driverso as to sample the input DC voltage and to provide a selector signalbased on the sampled input DC voltage to the driver to control operationof the driver.
 13. The converter of claim 12, wherein the selectorsignal indicates to the driver whether the converter circuit isconfigured as a buck-boost converter or as a flyback converter.
 14. Theconverter of claim 12, wherein the interface circuit comprises acurrent-sense amplifier for sensing the input DC voltage and inresponse, generating a sensor signal and further comprises a driverselector receiving the sensor signal, comparing the sensor signal to acomparison voltage, and based on the comparing, generating the selectorsignal.
 15. The converter of claim 14, wherein the current-senseamplifier is operable in a first state and a second state correspondingto connection of the current-sense amplifier to a high side and a lowside, respectively, of a power source supplying the input DC voltage andwherein the sensor signal is substantially equivalent in the first andsecond states.
 16. The converter of claim 12, wherein the driverincludes a logic circuit for generating the driver signal based theselector signal.
 17. A driver for use with multiple DC-to-DC convertertypes, comprising: means for sensing an input voltage from a powersupply and generating a sensor signal based on the sensing; means forcomparing the sensor signal to a comparison voltage and generating aselector signal based on the comparing, the selector signal indicatingone of the DC-to-DC converter types; and means for driving a DC-to-DCconverter circuit linked to the comparing and generating means as theone DC-to-DC converter type with a driver signal based on the selectorsignal.
 18. The driver of claim 17, wherein the sensing and generatingmeans comprises a voltage sensor sensing the input voltage andgenerating the sensor signal corresponding to the sensed input voltage,the voltage sensor comprising a current-sense amplifier.
 19. The driverof claim 18, wherein the current-sense amplifier is operable in a firststate and a second state corresponding to connection of thecurrent-sense amplifier to a high side and a low side, respectively, ofa power source supplying the input voltage and wherein the sensor signalis substantially equivalent in the first and second states.
 20. Thedriver of claim 17, wherein the converter types include flyback andbuck-boost and wherein the comparing and generating means comprises acomparator generating the selector signal by comparing the sensor signalto a comparison voltage, the selector signal indicating the convertertype being flyback or buck-boost.